If you're on Facebook at this point, it is simply not possible to exercise any form of privacy and confidentiality online. Every post, like, share, follow, friend, and engagement with the platform builds an online identity that you have little control over. Deleting your account is the only thing you can do to even start protecting your online information. If you're really serious you should consider deleting your posts, removing your likes, unfriending your contacts, and just scrubbing the account before deleting just to be thorough.
It's a good idea to get a feel for what information about you is out there already. Simply Google yourself and see what comes up. You may need to search with a few keywords if you have a generic name like "John Doe [state/province/city]" to narrow it down to you. From there start compiling a list of each site and what identifying information it has about you. Once you're done, start locking everything listed down or remove it.
A social graph simply represents you and your connections with other people. As far as your data is concerned you are a "node" and your engagements are "edges" on a graph. From a user perspective you are clicking a button to subscribe or add something to your favorites. As far as your data is concerned you are establishing an edge between your node and another node. The more you engage the more you build up a social graph. These graphs are what "the algorithm" runs on. This how websites know what content to recommend and hide from you. You can just as easily remove these edges between nodes by removing your likes and subscriptions. RSS feeds are particularly handy for this as they allow you to keep up to date with new content without needing to click a "subscribe" button on a website. All of your feeds are in one place locally on your computer and nobody can see the content you would otherwise be "subscribed" to or "following" such as on YouTube or Twitter. YouTube tries to bury their RSS feeds, but you can still get feeds for when a channel uploads a new video. Twitter doesn't have RSS feeds however Nitter is a Twitter front-end written in Nim which does allow you to have an RSS feed for Twitter accounts. Needless to say since RSS is an open cross-platform standard that can't be monetized; finding feeds can be difficult for other sites.